The Globe How to describe where you are, and how to find new places.
Intelligence Competition • To find who is smarter, males or females , we are going to conduct a scientific experiment. I will give the name of a place in Arizona. When you have located that place on the map, first. No cheating!
raise your hand . This is a timed test. The first 5 times will count for the team score. Lowest times win. Ladies
Ladies find • Sasabe Arizona
Guys find • Holy Joe Peak
Look in I 9
You need Coordinates (= two numbers) • One set across • One set • I 9 down • Start at logical point - on flat map, upper left corner (just like reading.) • Use letters or numbers BINGO!
Can we do this for the Earth?
(Photo of Earth here)
We have a problem!
• Spheres point.
don’t have a logical starting
BUT, The Earth rotates on its axis.
This gives us Two logical Starting points.
North Pole (How would You know if You were There?) Axis South Pole
You could then draw lines from one pole to the other.
Now, if you divide each of those lines in half and draw a line through the midpoints… You get the Equator
Next, draw lines around the Earth parallel to the equator .
Finally, we have our grid !
Remember from math Circles are divided into 360 degrees .
Latitude • Measures degrees north/south – also called parallels • Starting point: Equator 0º • Ending point: Poles 90 ° N,S • Equator separates North/South Hemispheres • Equator is a great circle – the only parallel great circle – What in the world is a GREAT CIRCLE ?
A great circle is the edge of a cut through the Earth passes through Earth’s center that
Longitude • Measures degrees east/west – also called meridians • Starting point: Prime Meridian 0º • Ending point: International Date Line 180º • Separates East/West hemispheres – every meridian and the one opposite make a great circle
Each Degree of Latitude (or Longitude at the Equator) • Represents ~69 miles • (360 x 69 = 24,840mi) • To be more precise: – each degree • 60 minutes • ~1.15 miles – each minute • 60 seconds • ~101 feet
Distance for a degree of longitude varies
Written Form latitude , longitude degrees minutes (&seconds) Phoenix: 33 º 26 ’ N , 112 º 04 ’ W MCC: 33 º 25 ’ N , 111 º 49 ’ W
International Meridian Conference • 1884 • 27 nations • Established Royal Observatory at Greenwich England as the Prime Meridian
Map Projections • A globe is not always the best representation of the Earth – Doesn’t show local detail – Lacks convenience - not portable
Map Projections • But a globe is the only true representation of: – direction – area – shape – distance